You don't need carbs
I found this graphic on Mark's Daily Apple, the website of Mark Sisson, author of The Primal Blueprint.
In the article in which this graphic is included, he states, "There is actually no requirement for any 'essential dietary carbohydrates' in human nutrition. It’s possible to live a very long and healthy life never consuming much – if any – in the way of carbs, provided you get adequate dietary protein and fat. The same can’t be said for going too long without protein or fat. Cut too far back on either of those macronutrients and you will eventually get sick and die."
That's a pretty bold statement that contradicts several other sources, but it's certainly what I've been found to be true about my body and carb intake.